The present invention relates to a copier, printer, facsimile apparatus or similar image forming apparatus and more particularly to an image forming apparatus including a revolver type developing unit.
An electrophotographic process using powdery toner for developing an image and an apparatus for practicing the same are conventional. For example, a monocolor or a full-color image forming apparatus of the type using two-ingredient type developers usually includes sensors each for sensing the toner content of a particular developer, i.e., so-called T sensors. This type of apparatus executes process control in accordance with the outputs of the T sensors in order to enhance image quality.
It is a common practice with, e.g., a color image forming apparatus to use a rotary developing unit (revolver hereinafter) having a plurality of developing sections arranged therein. The problem with this kind of apparatus is that leads, for example, cannot be connected to the revolver. It follows that even if sensors and other electrical loads are arranged in the revolver, signals output form the loads cannot be sent to the body of the apparatus. The apparatus therefore fails the execute sufficient process control.
In light of the above, Japanese Patent Laid-Open Publication No. 8-69144, for example, discloses an image forming apparatus using photoelectric transducers for feeding power to a revolver and receiving information from the revolver. Also, Japanese Patent Laid-Open Publication No. 10-133446 teaches the use of a current transformer for feeding power and the use of optical communication for interchanging signals.
However, the photoelectric transducer scheme cannot maintain an electromotive force derived from the emission of light stable due to the rotation of the revolver, resulting in unstable generation of power in the revolver. Further, the quantity of light available with a light source and therefore the electromotive force sequentially decreases due to the limited life of the light source. In addition, the light source emitting light within the apparatus body effects a photoconductive element or image carrier. Even the current transformer and optical communication scheme renders the power feed and signal interchange unstable due to the rotation of the revolver and is apt to obstruct the transfer of necessary signals.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 6-267627, 8-88600, and 11-174797.